1. Field of the Invention
The present invention relates to an apparatus and method for allocating a resource in a wireless communication system employing an orthogonal frequency division multiple access (OFDMA) scheme.
2. Discussion of the Background
In recent years, orthogonal frequency division multiplexing (OFDM) or orthogonal frequency division multiple access (OFDMA) has been used as a scheme for high-speed data transmission over a wired/wireless channel. The OFDM or OFDMA scheme refers to a data transmission scheme using a multi-carrier, in which serially input data is converted into parallel signals, the respective converted signals are modulated with mutually orthogonal sub-carriers, that is, sub-channels, and then the modulated signals are transmitted.
This OFDMA scheme can achieve improved transmission efficiency at high-speed data transmission by transmitting data while maintaining orthogonality between multiple sub-carriers. It is also characterized by good frequency efficiency and resistance to multi-path fading.
In addition, the OFDMA scheme is advantageous in that it is resistant to frequency-selective fading due to the use of an overlapped frequency spectrum, it can reduce the effect of inter-symbol interference (ISI) by using a guard interval, it makes it possible to more simply design an equalizer structure in hardware, and it is resistant to impulsive noise.
In a wireless communication system using the OFDMA scheme (hereinafter referred to as “OFDMA wireless communication system”), frequency-selective scheduling can be used to continuously allocate frequency resources with good channel conditions to one user. However, as frequency bands allocated to users gradually broaden, there are limitations in continuously allocating frequency resources with good channel conditions to one user in the OFDMA wireless communication system.